An Affidavit of Execution is a very simple document that allows your witnesses to swear under oath in the presence of a notary that they witnessed the signing of the Will. It is certainly not a requirement, because your document does not need to be notarized in order to be a legal Will.
To make your document a legal Last Will and Testament, it should be signed in the presence of two witnesses. These witnesses can be any two adults who are not beneficiaries in the Will.
If you do wish to have your Will notarized, you need your witnesses to sign an Affidavit of Execution, that is then attached to the Will. The Affidavit should be signed in the presence of a Notary or "Commissioner of Oaths". The form is so simple, and such a core part of any Notary's job, that they should be able to provide the document.
If your Notary is unable to provide one, please contact us and we can provide one for you. We have also provided a selection of a few through the following links. If your State is not there, you can either adapt one of the available documents, or contact us.